Next time you're stuck in traffic, quell your road rage by flashing a quick smile.

Researchers from the University of Kansas had college students hold chopsticks in their mouths to simulate either a smile or a neutral expression, and then induced a stressful situation. (Besides having chopsticks in their mouths.) The results? Smilers had lower heart rates and reduced stress responses compared to the straight-faced subjects.

Researchers believe that activating certain facial muscles--like those used to smile--sends a message to your brain: You're happy. Calm down.

Lead researcher Sarah Pressman, Ph.D., an assistant professor at the University of Kansas, explains: "It's not just that our brains are happy and make us smile, it can also be the opposite--we feel the smile and become happy," she says.

But here's the kicker: You don't have to actually be happy to reap the benefits. People in the study weren't necessarily in a good mood--they just faked a smile. So skip flipping off the guy who's driving like a jerk, and force a grin instead. Even though you may feel awkward, it's an easy way to break a very short stress response, says Pressman.